Composite beam structure and assembly

ABSTRACT

A composite beam structure is provided for the construction of walls, roofs, partitions, and other structural supporting assemblies. The beam structure utilizes side-to-side modular double-walled beams, interlocking along two edges on each side, and attached together. A high strength, lightweight composite structure is provided requiring no additional structural support members to secure each beam to an adjacent beam or to support the composite structure. The composite beam structure can be disassembled without destroying the beams and later reassembled at another location.

United States Patent Baker et al.

[ 1 COMPOSITE BEAM STRUCTURE AND ASSEMBLY [72] Inventors: William Baker,403 Loudonville Road, Albany, N.Y.; Clyde Worrell,

334 Southwest 12th Avenue, Boyn' ton; Donald Howard Banzhal, 5805Orchard Way, Palm Beach, both of Fla.

[22] Filed: Sept. 15, 1969 [21] Appl. No.: 9,252

[52] US. Cl. ..52/731, 52/729, 61/61, 52/627, 52/90, 52/593 [51] Int.Cl. ..E04c 2/40, E04c 3/04 [58] Field of Search ..61/61, 62, 58-60;52/730-732, 242, 716-718, 729, 629, 627, 628

[56] References Cited UNITED STATES PATENTS 835,863 11/1906 Otte..52/456 1,207,080 12/1916 Ruth ..52/730 1,426,277 8/1922 Conant..52/717 1,608,672 11/1926 Rappaport ..52/731 [4511 Oct. 17,1972

2,478,993 8/1949 Wing ..52/5 79 FOREIGN PATENTS OR APPLICATIONS 782,9006/1954 Great Britain ..52/90 264,468 l/1928 Great Britain ..61/62 47,4341/1937 France ..61/61 Primary Examiner-Frank L. Abbott AssistantExaminer-James L. Ridgill, Jr. Attorney-James & Chapman This applicationfiled under Rule 47a.

[57 ABSTRACT A composite beam structure is provided for the constructionof walls, roofs, partitions, and other structural supporting assemblies.The beam structure utilizes side-to-side modular double-walled beams,interlocking along two edges on each side, and attached together.

A high strength, lightweight composite structure is provided requiringno additional structural support members to secure each beam to anadjacent beam or I to support the composite structure. The compositebeam structure can be disassembled without destroying the beams andlater reassembled at another location.

I .26 Claims, 3 Drawing Figures COMPOSITE BEAM STRUCTURE AND ASSEMBLY Inaccordance with the present invention individual double walled modularbeam units of any desired shape and length having interlockingconnecting means for tightly and rigidly locating and securing adjacentbeam units together in a uniform coordinated structure are provided,requiring securing means such as rivets or bolts only to preventdetachment, and to completely rigidify the structure under the stress ofthe weight of a building, and to resist weather conditions. These can beassembled side-to-side, to form a high strength, lightweight, stablecomposite beam structure. The tightness of the assembly without securingmeans helps prevent the shearing of nuts and bolts, and rivets undersevere weather stresses. The composite beam assembly of this inventionrequires no independent structural or base supporting members, can beattached in a manner to permit disassembly without destroying the beamunits of which it is composed, and has means for securing and supportingheavy accessory equipment.

Preferred embodiments of the interlocking composite beam structure areshown in the drawings, in which:

FIG. 1 is a break-away perspective view of a plurality of modular beamunits assembled to form a composite beam structure of this invention;

FIG. 2 is a cross-sectional detailed view of the interlocking male andfemale connections of a typical beam of FIG. 1;

FIG. 3 is a partial cross-sectional view of a wall and roof section of abuilding constructed from the composite beam structure.

The composite beam structure of this invention as shown in FIG. 1 ismade up of a series of side-to-side interlockingly modular double walledsections or beam units, comprising inner sections 1 in the form of beamsand an outer section 2 in the form of a channel beam. The beam sections1 have two male flanges 5 running along the edges of the flanges 11a and11b. The flanges 5 are parallel to the flanges 11a and 11b and extendover the entire length of the beam. Female flange grooves 6 extend alongthe edges of flanges 12a and 12b at the other end of the beam. Thegrooves 6 are also parallel to the flanges and extend over the entirelength of the beam.

The interlocking connection of the end 5 and the groove 6 is best seenin FIG. 2. The edges of the long sides 61 of the recessed grooves 6 havetabs 62 extending outwardly at right angles. The tabs 62 form outsidechannels 64 which run parallel to the grooves 6 and have openings whichare flush with the outer surface of the flanges 12a and 12b. As shown inFIG. 1, by inverting one beam section with respect to the adjacent beamsection, the male flange end 5 of one section will interlock with thefemale flange groove 6 of the adjacent section, in a tight and rigidfit, and the tab 62 of the long leg 61 of the groove 6 will abut thebase portion 51 of the mating end 5.

Similarly, the outer channel beam 2 has an end 5 running along the edgeof flange 21 to engage the groove and the lip of the adjacent beamsection 1. In this manner, each beam unit is attached to the adjacentbeam unit along two edges.

The openings in the grooves 6 are formed slightly smaller than thethickness of the mating end 5, to firmly engage the end, and ensurethat. adjacent beams are securely held together prior to riveting. Inaddition, the abutment of the tabs 62 against the base portion 51 of theend provides both a large bearing surface for increased strength and astop to properly set the spacing between adjacent beams. The legs 61 ofthe groove 6 and the legs 52 of the flange also abut along their entirelength, thereby preventing the angular sideways movement of one beamwith respect to an adjacent beam. The beams are tightly secured :intheir interlocking position by rivets 25 which fasten through theabutting legs 61 and 52.

The inside comers of the channels 64 formed by the tabs 62 are providedwith shallow grooves 63, which run along the entire length of the beams.Inserts 8 having corresponding lips 81 can be installed therein and heldsecurely so that accessory equipment or additional structural membersmight be attached to either side of the composite beam structure. Theinserts can be simply snapped into the grooves 63 in a press fit, orslidably installed from the ends of the structure.

The building shown in FIG. 3 has walls and roofing sections 91a and 91bconstructed from the composite beam structure of this invention. Theuppermost wall beam 92 has a mitered edge which abuts the mitered edgeof roofing beam 98.. Reinforcement bars 93 and 94 are installed withinthe beams to provide a mounting base for tension casting 95 andcompression casting 96, respectively. Both the tension casting 95 andthe compression casting 96 are riveted to the beams 92 and 98 throughthe reinforcing bars 93 and 94, thus providing a rigid connectionbetween the roof 91b and wall 90. Similarly, the uppermost beams 99a and99b of the roofing sections 91a and 91b, respectively, both terminate ina mitered abutment at the peak of the roof. Ridge castings 97 areriveted to the roofing beams 99a and 99b through reinforcement bars 93and 94 to secure the two portions of the roof together. It can be seenfrom this illustration that similar connecting means can be used tosecure adjacent building sections of the composite beam structure havingany angle therebetween.

As is apparent from the drawings,

The modular beam unit is provided with two types of mating end shapes.One type is referred to herein as the male flange because the side wallof the beam terminates in a recessed single flange having two portions,a first portion turning inwardly towards the interior of the beamsubstantially at right angles to the side wall, and a second portionextending substantially parallel to the side wall and substantially atright angles to the inwardly turned first portion. The other type isreferred to herein as the female flange, because the side wall of thebeam terminates in a recessed double flange having two legs and threeportions, a first portion turning inwardly towards the interior of thebeam substantially at right angles to the side wall, a first legconstituting the second flange portion extending substantially parallelto the side wall and substantially at right angles to the inwardlyturned first portion, and a second leg con stituting the third flangeportion extending substantially parallel to the side wall substantiallyat right angles to the inwardly turned portion, and substantiallyparallel to the first leg, the first and second legs defining a socketsubstantially parallel to the side wall for reception of the male flangeand into which the single male flange of an adjacent beam fits snuglyand rigidly. These members can mate in a press fit, if desired, forgreater rigidity, but this is not essential, since the adjacent beamunits can be attached together by any conventional securing means. Inthe composite beam assembly, the single male flange and one of the wallsof the double female flange of adjacent beam units abut throughout theirlength to form a continuous connection, which is firmly secured toprevent separation under the stresses experienced in structuralassemblies by means of rivets or bolts. Externally of the composite thefemale shaped flange also defines with the outer side of the beam unitsa channel-into which other structural elements can be fitted. Theabutting double female flange wall is preferably formed with an endturned to match the recess of the single flange wall, for betterrigidity in interlocking.

Preferably, two side walls of each beam section having mating ends ofthe male type, and two side walls have mating ends of the female type.Likewise, the channel beam section has an male type mating end, on oneside, while the other side has a female type mating end. The two matingends on each side of the beam sections are preferably of the same type,either male or female.

The long legs of the recessed male flanges are parallel to the sides ofthe beam units, and extend over the entire length of the beam unit.Similarly, the corresponding recessed female type ends are also parallelto the sides of the beam, and extend over the entire length of the beam.The curved base portion of the female end is designed to mate with theedge of the male end. The openings in the grooves are formed slightlysmaller than the thickness of the mating flange so that the grooves willsecure the flange in a relatively tight and rigid connection. Thisallows the assembly of several interlocking beams of the composite andholds them against separation and structural collapse prior to and afterbolting or riveting. In addition, to provide further strength, the endof the long leg of each female groove, which is the outermost edge ofthe flange, is formed into a tab extending outwardly at right angles.When a beam is assembled to an adjacent beam, the male ends will engageand interlock the female grooves, and be securely held thereby, and thetabs will abut the base portion of the male ends to properly control theextend of interlocking. This ensures uniform strength of eachinterlocking connection. It also ensures constant spacing between eachbeam, thereby allowing accurate layoutand predrilling of rivet and boltholes in advance, without the need for measurement upon the installationof each beam. The abutment of the tabs and the base portion of the maleends provides a relatively large bearing surface between adjacent beams,which results in the increased strength and rigidity of the compositebeam structure. Furthermore, the abutment of the flange walls themselvesalong the entire length of two edges of each mating beam substantiallyprevents angular movement of one beam with respect to an adjacent beam,thus reducing the bending stresses that might be placed upon a rivet orbolt. Since compressive loads are supported primarily by the abutment ofthe mating interlocking connections, the shear stress placed upon therivets or bolts and the bearing stress placed'upon beams at the locationof the rivet or bolt holes are extremely low. Therefore, relatively fewrivets or bolts are required to firmly and sufficiently, secure adjacentbeams. These factors facilitate rapid assembly of a composite beamstructure and reduce the cost of construction.

The tabs at the ends of the female grooves also complete the formationof channels which run perpendicularly to the female grooves and haveopenings flush with the outer surface of the flanges. The inside cornersof the channels can be provided with shallow grooves which run along theentire length of the beam. Inserts having corresponding lips can beinstalled therein, and held securely, so that other structural membersor accessory equipment can be mounted to either side of the compositebeam structure. The inserts can be made to snap into the grooves of thechannels, or merely slide in from one end of a beam. In either case,accessory or structural members attached to the inserts or themselvesformed to engage the channels may be assembled to and disassembled fromthe composite beam structure without the need for extensive tooling, andwithout the danger of damaging either the beam structure or theaccessory equipment. Since every female groove has a channel, and eachchannel extends over the entire length of the beam unit, it is possibleto easily mount additional members in any convenient location on eitherside of the composite beam structure.

Because the beam units are held together in a tight and rigid fit, thedouble walled composite beam structure can be assembled quite easily,and supplemental fasteners such as rivets or bolts are needed only tohold the interlocking beams securely together. The interlocking maleends and female grooves, which secure each beam to an adjacent beamalong two edges, provide excellent strength and rigidity in use in manyconstruction applications. The beams are particularly useful indismantlable wall and divider structures, which can be taken apart andstored in a small space.

The length of the sides of the beam members and their spacing by thecrosspiece of the beams are determined by, and themselves determine, thesize of and the number of units needed to form a composite beamassembly. For optimum strength and rigidity, the side walls and thecrosspieces are relatively short, and are of approximately the samelength (measuring the length of each of the four side walls from thecrosspiece). Depending upon the strength of the material used, they canhowever, differ in length by ratio of as much as 10 to 1, withoutbecoming unduly weak. Furthermore, if the sides are unusually long,relative to a crosspiece, several crosspieces can be used. However, theshorter the sides, the more versatile are the beam units in formingcomposite structures of varying size.

The composite beam structure can be assembled so that the beams runeither horizontally or vertically. It is therefore, possible to design astructure having a minimum number of joints. For example, a horizontalarrangement for a long relatively low wall would result in far fewerconnections, and a correspondingly lower labor cost than a verticalarrangement. In other words, the composite beam structure of thisinvention possesses sufficient strength and versatility to be utilizedin the most efficient and economical manner suitable for the particularconstruction. It is important to note that the economics of constructionare greatly enhanced by the fact that, except for the length, all beamsections are exactly alike. Similarly, all channel or U-beam sectionsare exactly alike. Each beam unit has two male and two femaleinterlocking connections, and thus each can be fitted to an adjacentunit, regardless of which side the female or male fittings are on. Massproduction manufacturing and inventory techniques can, therefore, beapplied, and the cost of manufacture and storage kept to a minimum.Similarly, the user need not store predetermined numbers of female andmale units, as would be the case were each unit to have fittings only ofone type.

Each beam can be formed by extruding, rolling, milling, casting orforging the desired material. Structural metals, such as aluminum andsteel, are the most desirable, since they have a relatively low cost,are easy to form and most importantly, provide the required strengthnecessary for construction. Aluminum is the preferred metal, since itprovides strength and formability and can be inexpensively renderedcorrosion resistant and be decoratively colored by anodizing. Othermaterials, such as wood, construction glass, ceramics, and plastics suchas nylon, polystyrene, polypropylene, polycarbonates, andpolytetrafiuoroethylene can also be utilized. Although these materialsmay not possess the strength of metallic material, they are readilyformed into the desired shapes, and are lightweight, and noncorrodible.Therefore, in certain applications they may be more desirable thanmetallic materials.

The beams can be fastened together by any conventional securing means.These include nuts and bolts, rivets, screws and clamps. For permanentconstruction of the beam configuration of this invention rivets arepreferred, since they can be rapidly assembled and provide the necessarystrength. On the otherhand, however, for temporary facilities, nuts andbolts or screws are preferred, since they can be readily removed toallow for the disassembly of the beams.

The side walls of the beam structure enclose openended air chamberswhich reduce the weight of the beam structure, and also provideinsulation against the passage of both heat and sound. The. insulatingeffect can be increased, if desired, by closing. off the open ends, andby filling the chambers with additional insulating material beforeassembly of the beams.

Due to its versatility and strength, the composite beam structure ofthis invention can be utilized for outer walls, roofing sections, innerpartitions, and many other structural elements. In addition, the beamstructure of this invention is also particularly useful for theconstruction of temporary buildings or other temporary facilities. Sincethe interlocking beam structure can be secured by detachable securingmeans, it can be disassembled without destroying the beams by simplyremoving the securing means, i.e., rivets or bolts, and then can bereused at a subsequent facility. Both the male end and female grooveconnecting means and the lightweight hollow construction makedisassembly and reassembly elsewhere both feasible and practical.

The strong lightweight construction of the composite beam structure ofthis invention allows assembled partitions or walls to be readily movedwithout disassembly. If such walls or partitions are provided withwheels, their movement to alter the size of a room or change the layoutof a building can be readily accomplished.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. A modular box beam structure comprising a plurality of modularintegral beam units selected from I- and C-beam units joined togetherside-to-side in a push-in interlocking relation, the beam units having aweb and two flanges in the C-units and a web and four flanges in theI-units, the flanges of adjacent beam units being interlocked in pairs,of which pairs one flange on one unit terminates in an open femalechannel extend ing from the flange along the beam with the openingleading into the channel facing away from the flange and towards theadjacent beam, and substantially in parallel to the flange, and theother flange on the other unit terminates in a male member extendingfrom the flange along the beam facing away from the flange and towardsthe adjacent beam, and substantially in parallel to the flange, inalignment with the female channel, the male member being inserted in thefemale channel in a snug and rigid push-in joint, and fastening meansextending through the male-in-female channel joint, interlockingadjacent land C-beam units together, and preventing withdrawal of themale members from the channels.

2. A modular box beam structure in accordance with claim 1, comprisingone I-beam unit and two C-beam units.

3. A modular box beam structure in accordance with claim 1,comprising'at least two I-beam units and two C-beam units.

4. A modular box beam structure in accordance with claim 1, comprisingat least two I-beam units and no C- beam units.

5. A modular box beam structure in accordance with claim 1, in which theouter channel walls of the female channel members are flushwith theouter side walls of the flanges.

6. A modular box beam structure in accordance with claim 1, comprisingmodular integral C-beam units attached to and closing off the open endsof terminal I- beam units, the C-beam units having a web and twoflanges, of which one terminates in an open female channel extendingalong the flange and the other terminates in a male member extendingalong the flange, interlocking with the male member and female channel,respectively, of the terminal l-beam, and fastening means extendingthrough both joints and attaching them together.

7. A modular box beam structure in accordance with claim 1,comprisingland C-beam units, each having at least one male member andone female channel.

8. A modular box beam structure in accordance with claim 5, in which theI-beam units each have two male members and two female channels, oneeach on each side of the I-beam unit.

9. A modular box beam structure in accordance with claim 1, in which themale members extend over the entire length of the beams; thecorresponding female channels extend overthe entire length of the beams;and the male members engage the base portions of the channels over theentire length of the beams.

10. A modular box beam structure in accordance with claim 9, in whichthe male members and the female channels are inward of the flanges, andthe outermost edges of one of the channel walls have tabs extendingoutwardly of the flanges substantially at right angles thereto, and saidtabs abut the base portion of the flanges adjacent the mating malemembers and control the extent of the interlocking of the male membersand female channels, and increase the bearing surface between adjacentI-beam units.

11. A modular box beam structure in accordance with claim 10, in whichthe tabs and female channels define channels running externally of thebeam units along the entire length of the beams, and inserts in thechannels, to attach additional structural members and accessoryequipment to the exterior side of the beam.

12. A modular box beam structure in accordance with claim 1, in whichthe l-beam section male members have a first portion turned inwardlyfrom the flange towards the interior of the beam substantially at rightangles to the flange, and a terminal portion extending substantiallyparallel to the flange and substantially at right angles to theinwardly-turned first portion; and the female channels have a firstportion turning inwardly towards the interior of the beam substantiallyat right angles to the flange, an outer channel wall extendingsubstantially parallel to the flange and substantially at right anglesto the inwardly-turned first portion, and an inner channel wallextending substantially parallel to the flange substantially at rightangles to the inwardly-turned first portion, and substantially parallelto the outer channel wall, defining therebetween a channel whose openingis substantially in parallel to the flange and in alignment,side-to-side, with the male member of an adjacent beam.

13. A modular box beam structure in accordance with claim 12, in whichthe openings in the channels are smaller than the thickness of thecorresponding male members so that the channels firmly engage the malemembers in a tight and rigid fit.

14. A modular box beam structure in accordance with claim 12, in whichthe terminal ends of the outer channel walls of the female channels havetabs extending outwardly thereof substantially at right angles thereto,and said tabs abut the base portion of the mating male members andcontrol the extent of interlocking and increase the bearing surfacebetween adjacent beams, and define external channels running along thebeams for reception of inserts,

15. A modular box beam structure in accordance with claim 14, in whichthe external channels have openings flush with the sides of the flangesand have grooves formed at their inside corners running along the entirelength of the beams; and inserts having lips which correspond to thegrooves on the inside corners of the channels installed and heldsecurely in the channels, to attach additional structural members andaccessory equipment to either side of the composite beam structure.

16. A modular box l-beam or C-beam unit for tight and rigid side-to-sideinterlocking connection to adjacent like modular beam units to form amodular unit building beam structure, comprising a web having at leasttwo flanges, the flanges being selected from flanges terminating in amale member extending outwardly from and substantially in parallel tothe flange, and flanges terminating in a female channel extendingoutwardly from and along the flanges with the opening leading into thechannel facing outwardly from the channel substantially in parallel tothe flanges and in interlocking alignment with the male member of anadjacent beam unit, the male member and female channel being adapted toengage corresponding female and male members, respectively, of anadjacent beam unit snugly and rigidly in a side-to-sidemale-in-femalechannel push-in-joint over a length sufficient to receivefastening means extending through both and attaching them together.

17. A modular box beam unit in accordance with claim 16, in which theopenings in the channels are smaller than the thickness of the malemember, so that the channel socket will firmly engage the male member ofan adjacent beam unit.

18. A modular box beam unit in accordance with claim 16, in which themale member and the female channel each extend over the entire length ofthe beam, and the male member will engage the base portion of thechannel of an adjacent beam unit, and the outer wall of the femalechannel is flush with the outer side wall of the flange of the adjacentbeam unit upon assembly thereto.

19. A modular box beam unit in accordance with claim 16, in the form ofa C-beam having one male member and one female channel.

20. A modular box beam unit in accordance with claim 19, in the form ofan l-beam having two male members and two female channels.

21. A modular box beam unit in accordance with claim 16, in which theterminal end of the outer channel wall of the female channel has a tabextending outwardly substantially at right angles thereto; and said tababuts the base portion of the flange adjacent the mating male member tocontrol the extent of interlocking of the male members and femalechannel and increase the bearing surface within adjacent beam units.

22. A modular box beam unit in accordance with claim 21, in which thetab and outer wall of the female channel form a channel runningexternally to the beam unit and along the entire length of the beam tosecure inserts having corresponding lips which can be installed thereinand held securely, to attach additional structural members and accessoryequipment to the beam.

23. A modular box beam unit according to claim 16, in which the malemember has a first portion turned inwardly from the'flange towards theinterior of the beam unit substantially at right angles to the flangeand a terminal portion extending substantially parallel to the flangeand substantially at right angles to the inwardlyturned first portion;and the female channel has a first portion turned inwardly towards theinterior of the beam unit substantially at right angles to the flange,an outer channel wall extending substantially parallel to the flange andsubstantially at right angles to the inwardly-turned first portion, andan inner channel wall extending substantially parallel to the flangesubstantially at right angles to the inwardly-turned first portion, andsubstantially parallel to the outer channel wall, defining therebetweena channel whose opening is substantially in parallel to the flange andin alignment, side-to-side, with the male member of an adjacent beamunit.

24. A modular box beam unit in accordance with claim 23, in which theopening in the channel is smaller than the thickness of the male member,so that the channel will firmly engage the male member of an adjacentbeam unit in a tight and rigid fit upon insertion therein.

25. A modular box beam unit in accordance with claim 23, in which theterminal end of the outer channel wall of the female channel has a tabextending outwardly thereof substantially at right angles thereto, andsaid tab abuts the base portion of the mating male member to control theextent of interlocking and in-

1. A modular box beam structure comprising a plurality of modularintegral beam units selected from I- and C-beam units joined togetherside-to-side in a push-in interlocking relation, the beam units having aweb and two flanges in the C-units and a web and four flanges in theI-units, the flanges of adjacent beam units being interlocked in pairs,of which pairs one flange on one unit terminates in an open femalechannel extending from the flange along the beam with the openingleading into the channel facing away from the flange and towards theadjacent beam, and substantially in parallel to the flange, and theother flange on the other unit terminates in a male member extendingfrom the flange along the beam facing away from the flange and towardsthe adjacent beam, and substantially in parallel to the flange, inalignment with the female channel, the male member being inserted in thefemale channel in a snug and rigid push-in joint, and fastening meansextending through the male-in-female channel joint, interlockingadjacent I- and C-beam units together, and preventing withdrawal of themale members from the channels.
 2. A modular box beam structure inaccordance with claim 1, comprising one I-beam unit and two C-beamunits.
 3. A modular box beam structure in Accordance with claim 1,comprising at least two I-beam units and two C-beam units.
 4. A modularbox beam structure in accordance with claim 1, comprising at least twoI-beam units and no C-beam units.
 5. A modular box beam structure inaccordance with claim 1, in which the outer channel walls of the femalechannel members are flush with the outer side walls of the flanges.
 6. Amodular box beam structure in accordance with claim 1, comprisingmodular integral C-beam units attached to and closing off the open endsof terminal I-beam units, the C-beam units having a web and two flanges,of which one terminates in an open female channel extending along theflange and the other terminates in a male member extending along theflange, interlocking with the male member and female channel,respectively, of the terminal I-beam, and fastening means extendingthrough both joints and attaching them together.
 7. A modular box beamstructure in accordance with claim 1, comprising I- and C-beam units,each having at least one male member and one female channel.
 8. Amodular box beam structure in accordance with claim 5, in which theI-beam units each have two male members and two female channels, oneeach on each side of the I-beam unit.
 9. A modular box beam structure inaccordance with claim 1, in which the male members extend over theentire length of the beams; the corresponding female channels extendover 17 the entire length of the beams; and the male members engage thebase portions of the channels over the entire length of the beams.
 10. Amodular box beam structure in accordance with claim 9, in which the malemembers and the female channels are inward of the flanges, and theoutermost edges of one of the channel walls have tabs extendingoutwardly of the flanges substantially at right angles thereto, and saidtabs abut the base portion of the flanges adjacent the mating malemembers and control the extent of the interlocking of the male membersand female channels, and increase the bearing surface between adjacentI-beam units.
 11. A modular box beam structure in accordance with claim10, in which the tabs and female channels define channels runningexternally of the beam units along the entire length of the beams, andinserts in the channels, to attach additional structural members andaccessory equipment to the exterior side of the beam.
 12. A modular boxbeam structure in accordance with claim 1, in which the I-beam sectionmale members have a first portion turned inwardly from the flangetowards the interior of the beam substantially at right angles to theflange, and a terminal portion extending substantially parallel to theflange and substantially at right angles to the inwardly turned firstportion; and the female channels have a first portion turning inwardlytowards the interior of the beam substantially at right angles to theflange, an outer channel wall extending substantially parallel to theflange and substantially at right angles to the inwardly-turned firstportion, and an inner channel wall extending substantially parallel tothe flange substantially at right angles to the inwardly turned firstportion, and substantially parallel to the outer channel wall, definingtherebetween a channel whose opening is substantially in parallel to theflange and in alignment, side-to-side, with the male member of anadjacent beam.
 13. A modular box beam structure in accordance with claim12, in which the openings in the channels are smaller than the thicknessof the corresponding male members so that the channels firmly engage themale members in a tight and rigid fit.
 14. A modular box beam structurein accordance with claim 12, in which the terminal ends of the outerchannel walls of the female channels have tabs extending outwardlythereof substantially at right angles thereto, and said tabs abut thebase portion of the mating male members and control the extent ofinterlocking and increase the bearing surface between Adjacent beams,and define external channels running along the beams for reception ofinserts.
 15. A modular box beam structure in accordance with claim 14,in which the external channels have openings flush with the sides of theflanges and have grooves formed at their inside corners running alongthe entire length of the beams; and inserts having lips which correspondto the grooves on the inside corners of the channels installed and heldsecurely in the channels, to attach additional structural members andaccessory equipment to either side of the composite beam structure. 16.A modular box I-beam or C-beam unit for tight and rigid side-to-sideinterlocking connection to adjacent like modular beam units to form amodular unit building beam structure, comprising a web having at leasttwo flanges, the flanges being selected from flanges terminating in amale member extending outwardly from and substantially in parallel tothe flange, and flanges terminating in a female channel extendingoutwardly from and along the flanges with the opening leading into thechannel facing outwardly from the channel substantially in parallel tothe flanges and in interlocking alignment with the male member of anadjacent beam unit, the male member and female channel being adapted toengage corresponding female and male members, respectively, of anadjacent beam unit snugly and rigidly in a side-to-sidemale-in-female-channel push-in-joint over a length sufficient to receivefastening means extending through both and attaching them together. 17.A modular box beam unit in accordance with claim 16, in which theopenings in the channels are smaller than the thickness of the malemember, so that the channel socket will firmly engage the male member ofan adjacent beam unit.
 18. A modular box beam unit in accordance withclaim 16, in which the male member and the female channel each extendover the entire length of the beam, and the male member will engage thebase portion of the channel of an adjacent beam unit, and the outer wallof the female channel is flush with the outer side wall of the flange ofthe adjacent beam unit upon assembly thereto.
 19. A modular box beamunit in accordance with claim 16, in the form of a C-beam having onemale member and one female channel.
 20. A modular box beam unit inaccordance with claim 19, in the form of an I-beam having two malemembers and two female channels.
 21. A modular box beam unit inaccordance with claim 16, in which the terminal end of the outer channelwall of the female channel has a tab extending outwardly substantiallyat right angles thereto; and said tab abuts the base portion of theflange adjacent the mating male member to control the extent ofinterlocking of the male members and female channel and increase thebearing surface within adjacent beam units.
 22. A modular box beam unitin accordance with claim 21, in which the tab and outer wall of thefemale channel form a channel running externally to the beam unit andalong the entire length of the beam to secure inserts havingcorresponding lips which can be installed therein and held securely, toattach additional structural members and accessory equipment to thebeam.
 23. A modular box beam unit according to claim 16, in which themale member has a first portion turned inwardly from the flange towardsthe interior of the beam unit substantially at right angles to theflange and a terminal portion extending substantially parallel to theflange and substantially at right angles to the inwardly turned firstportion; and the female channel has a first portion turned inwardlytowards the interior of the beam unit substantially at right angles tothe flange, an outer channel wall extending substantially parallel tothe flange and substantially at right angles to the inwardly turnedfirst portion, and an inner channel wall extending substantiallyparallel to the flange substantially at right angles to the inwardlyturned first portion, and substantially parAllel to the outer channelwall, defining therebetween a channel whose opening is substantially inparallel to the flange and in alignment, side-to-side, with the malemember of an adjacent beam unit.
 24. A modular box beam unit inaccordance with claim 23, in which the opening in the channel is smallerthan the thickness of the male member, so that the channel will firmlyengage the male member of an adjacent beam unit in a tight and rigid fitupon insertion therein.
 25. A modular box beam unit in accordance withclaim 23, in which the terminal end of the outer channel wall of thefemale channel has a tab extending outwardly thereof substantially atright angles thereto, and said tab abuts the base portion of the matingmale member to control the extent of interlocking and increase thebearing surface between adjacent beams, and define an external channelrunning along the beam unit for reception of inserts.
 26. A modular boxbeam unit in accordance with claim 25, in which the external channel hasan opening flush with the side of the flange and has grooves formed onits inside corners running along the entire length of the beam, tosecure inserts having corresponding lips which can be installed thereinand held securely, to attach additional structural members and accessoryequipment to the beam.